Research Only Immune & Anti-Inflammatory

Cathelicidin

also known as: hCAP-18, CAMP, Cathelicidin Antimicrobial Peptide

The parent of LL-37 — the sole human cathelicidin, whose expression is directly regulated by vitamin D and whose cleavage product LL-37 is a key effector of innate antimicrobial defense.

An 18 kDa cationic antimicrobial protein stored in neutrophil specific granules, cleaved by proteinase 3 to release the 37-amino-acid active peptide LL-37, linking vitamin D status directly to antimicrobial capacity.

Mechanism of action

hCAP-18 is stored in neutrophil secondary granules and released upon activation. Proteinase 3 cleaves the cathelin pro-domain to release LL-37, which: (1) disrupts microbial membranes via carpet/toroidal pore models; (2) neutralizes LPS endotoxin; (3) chemoattracts immune cells via FPR2/ALX receptor; (4) promotes wound healing via EGFR transactivation; (5) modulates TLR signaling. Expression upregulated by 1,25-dihydroxyvitamin D3 via VDR/RXR binding to the CAMP gene promoter.

Primary uses

Innate immunity research
Vitamin D-antimicrobial axis studies
Antimicrobial peptide drug development
Wound healing research

Typical dosing

Not established

Endogenous protein/peptide. Not administered therapeutically. LL-37 derivatives in preclinical development.

Regulatory status

Not approved as a therapeutic. LL-37 and fragments (FK-13, KR-12) are active areas of antimicrobial peptide drug development.

References

[review] Vandamme D, et al. "A comprehensive summary of LL-37, the factotum human cathelicidin peptide." Cell Immunol, 2012;280:22-35.
[pubmed] Liu PT, et al. "Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response." Science, 2006;311:1770-1773.

Related peptides

LL-37

The only human cathelicidin — an antimicrobial peptide with direct activity against bacteria, fungi, viruses, and biofilms, with additional roles in wound healing and immune signaling.

FK-13

The 13-residue FKRIVQRIKDFLR central fragment of LL-37 — the smallest LL-37 fragment that retains broad-spectrum antimicrobial activity while losing much of the parent peptide's cytotoxicity toward mammalian cells. Research-only; no clinical development program.

KR-12

KRIVQRIKDFLR — the minimal 12-residue bactericidal fragment of LL-37. Retains selective antimicrobial activity while losing LL-37's host-cell toxicity, making it the canonical template for LL-37-derived antimicrobial peptide drug discovery. Research-only.

HNP-1

The prototype human α-defensin — isolated from neutrophil granules by Ganz, Selsted and Lehrer in 1985; the dominant antimicrobial peptide in human neutrophils and a workhorse molecule of innate immunity. Research peptide only: no defensin has ever been developed as an approved drug.

hBD-2

The inducible β-defensin — cloned by Harder, Bartels, Christophers and Schröder (Nature 1997) from the lesional scales of psoriasis patients, with the paper framing psoriatic skin as a paradoxical "almost-never-infected" phenotype driven by massive β-defensin induction. Induced by TLR / NF-κB signalling in response to bacterial lipopolysaccharide and pro-inflammatory cytokines (IL-1, TNF-α).

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.